Various devices of such kind have been heretofore proposed as, for example, electrode contact type devices constituting a thin film switch, optical matrix devices comprising a combination of a light pen and a photodetector for detecting coordinates by obstructions of optical paths, pressure type devices for detecting the pressure applied by touch, and surface acoustic wave devices for determining coordinates based on propagation time taken by a surface acoustic wave.
Among these devices, the electrode contact type devices are simpler in structure and cheaper than the other devices. However, coordinate input devices of the conventional electrode contact type structure tend to cause a higher contact resistance and are mechanically fragile, because those devices have been keyboard switches using a transparent plastic film on which a thin sheet of a metal, such as Ag and Pd, or a thin film of an oxide metal, such as In.sub.2 O.sub.3 is formed over a given area by evaporation or sputtering. Therefore, these coordinate input devices have a poor yield and a short life. In one of the aforementioned thin film electrodes, fine powder of an electrically conductive metal is dispersed in a synthetic resin. However, the powder is not uniformly dispersed, and an accurate detection of coordinates is not possible. Further, a sufficient strength cannot be obtained.